Cutting elements, such as those used with bits for drilling earth formations, known in the art include a diamond surface layer or diamond table disposed onto a carbide substrate. The diamond table is used to provide properties of improved wear and abrasion resistance, relative to the underlying substrate, and the substrate is used to provide an attachment structure to facilitate attachment of the cutting element to an end-use machine tool, e.g., a drill bit or the like.
Such known cutting elements have a diamond layer or diamond table formed from polycrystalline diamond (PCD) and make use of a carbide substrate such as WC-Co. While the diamond layer operates to provide improved wear and abrasion resistance to the cutter, e.g., when compared to cutting elements having a wear surface formed from tungsten carbide, the diamond layer is known to have a coefficient of thermal expansion that is much lower than that of the underlying substrate. Accordingly, the high-pressure/high-temperature process used to sinter the diamond layer, form the PCD and attach the PCD layer to the underlying substrate is one that is known to produce a cutting element having residual compressive stress. The presence of such residual compressive stress induced on the diamond layer and substrate may result in cutting element breakage or diamond layer delamination under drilling conditions.
Attempts to improve the service life of such cutting elements have focused on reducing the residual compressive stress at the diamond layer-substrate interface, thereby reducing or minimizing the event of breakage, fracture or delamination under drilling conditions. While such efforts may be useful in reducing or minimizing instances of breakage or delamination, such performance gains are provided at the expense of compromising the wear resistance and resistance to crack initiation at the surface of the diamond table, which also operates to limit the effective service life of the cutting element.